1. Field of Invention
The present invention relates to a display. More particularly, the present invention relates to an electronic paper display.
2. Description of Related Art
The electronic paper display (EPD) possesses the advantages of high contrast (the same as that of regular paper) and low power consumption, and is light and flexible. Users of electronic paper displays not only enjoy an experience as if they are reading a book, but also have the ability to update data at the same time.
The electronic paper display was first developed in the 1970s. Such a first-generation EDP comprises many small charged balls that are white on one side and black on the other side. The balls rotate to show different colors under a varied electric field. Second-generation electronic paper displays were developed in the 1990s. In a second-generation EDP, microcapsules filled with colored oil and charged white particles replace the small charged balls. An external electric field controls the movement of the white particles. The display shows a white color when the white particles move upward (toward the user), while it shows the color of the oil when the white particles move downward (away from the user).
The electronic paper display comprises two glass substrates. There are two conductive layers coated on these two glass substrates respectively as top and bottom electrodes for changing the color displayed via the movement of the charged particles when power is applied. In order to enable smooth packaging of the display, the display borders on the bottom glass substrate are typically marked to facilitate positioning. However, since the materials of the conductive layers (for example, Indium Tin Oxide, ITO) are mostly transparent, an oxidation-reduction reaction easily occurs on the parts of the conductive layer on the top glass substrate corresponding in location to the borders when the EDP is operated under high-temperature conditions or for long periods. Therefore, the impedance of the electrode becomes extremely high. Moreover, border-shaped insulating bands are formed, resulting in abnormal display since voltage is unable to enter into a display zone.